"There's a theory that we use
money because without it, we would do much worse, in terms of
trade," said study lead author Gabriele Camera, a professor at
the Economic Science Institute at Chapman University in Orange,
Calif. But this theory hasn't yet explained the role of human
behavior in trading, he said.

Early human civilizations survived by sticking together in small
groups and trading within them, but modern societies are largely
based on transactions between strangers. The researchers wondered
what drives cooperation between people who don't know each other.
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In the study, the researchers examined human interactions in a
control setting — in which there were no incentives to cooperate,
but also no incentives not to cooperate — and found that people
were primarily self-interested. To evaluate the degrees of
cooperation, the participants played a "helping game," in which
they had to consider the costs and benefits of helping an
anonymous stranger. Camera and his colleagues observed these
interactions in groups of two, four, eight and 32 people.

"They did not trust each other in the control conditions when
they had nothing to exchange," Camera told LiveScience. In
particular, as group sizes increased, people were more wary of
others, he added.

The researchers then introduced tokens, which had no value
outside of the laboratory, to see if they affected levels of
trust and cooperation between the study participants. The
researchers found that when tokens were involved, people became
more likely to cooperate. Individuals started giving out
tokens in exchange for help, and expecting tokens when they
extended help to others.

"It's not that they trusted others, but they trusted that others
would help in exchange for a token," Camera explained. "This
object, which has no intrinsic value, acquired value and became a
symbol of trust."

The tokens also encouraged greater cooperation in large groups,
but once again, only in situations where the valueless tokens
acted as currency, and could be given or received as part of a
transaction.

"There was a clear social cost from using the tokens," Camera
said. "Cooperation did increase relative to the control economies
without tokens, but in situations where people had no more
tokens, sellers were unwilling to cooperate."

The findings suggest money plays an important sociological — and
not simply economical — role in modern societies.